The string lamp is widely used for indoor or outdoor decoration as a requisite ornament in festival celebration. The string lamp mainly refers to decorative lamps connected in series in an electrical circuit, and typically has an elongated lamp bulb, a lamp holder for fixing the lamp bulb, and a connecting base for achieving electrical connection between the lamp bulb and a lead wire. A plurality of string lamps are connected with one another in series through lead wire segments with metal conductive terminals fixed at two ends. The conductive terminals of these lead wire segments are inserted into the connecting base from the bottom of the connecting base to be in electrical connection with lamp pins of the lamp bulb. Wherein, the principle of the string lamp is disclosed in the Chinese invention patent No. CN201320549905.5, filed on Sep. 5, 2013, as described above.
However, during the use of the string lamp with this structure for decoration, when a lead wire is subjected to lateral tension relative to the connecting base of the string lamp (the lead wire segment between the adjacent lamp holders is straightened perpendicular to an optical axis), some of the conductive terminals are inclined in the connecting base due to the tension, and finally likely to be pulled out from the bottom of the connecting base, resulting in potential safety hazards or extinguishment and failure of the string lamp, which also does not meet the requirements of American safety regulations.
To overcome this disadvantage, a decorative lamp manufacturer adds a false line on the string lamp, and the false line 81 and the lead wire segment 82 are stranded together, as shown in FIG. 1. In this way, under normal circumstances, when an electrical line is subjected to lateral tension, the false line can bear most of a tensile force, and the stress on the end of the lead wire segment and the conductive terminals is very low, so that their positions relative to the inner wall of the connecting base are unlikely to change, and they are unlikely to be pulled out from the bottom of the connecting base. Thus, commercially available string lamps used on Christmas trees in America are all in the form of double-line stranding. However, if the false line and the lead wire segment are not tightly stranded or copper sheets on the conductive terminals are obliquely embedded into the connecting base, when the electrical line is subjected to tension, some of the conductive terminals can also be pulled out, resulting in potential safety hazards. In addition, in this way, machining and manufacturing processes become complicated, the product cost becomes high, the quality is inconsistent, and manpower and material resources are wasted.